Apparatus for producing hollow articles by immersion



May 6,1941. A...BO ECLER ETAL 1 2,241,176

APPARATUS FOR PRODUCING HOLLOW ARTICLES BY- IMMERSION Filed July 9, lg38' 4 Sheets-Sheet 1 QED May 6, 1941. A. BOECLER' ETAL Filed July 9, 1938 4 Sheets-Sheet. 2

vek/ors 13.112

May 6, 1941. A. BOEQLER I A 2,241,176

APPARATUS FOR PRODUCING HOLLOW ARTICLES BY IMMERSION Filed July 9, 1938 4 Sheets$heet s Jpven/ons May 6, 1941. A. BOECLER EIAL APPARATUS FOR PRODUCING HOLLOW ARTICLES BY IMMERSION Filed July 9. 1958 4 Sheets-Sheet 4' emars b5:

Patented May 6, 1941 APPARATUS FOR PRODUCING HOLLOW ARTICLES BY IM'MERSION Albert Boecler, Berlin, and Kurt Bratring,

Dahlcm, Berlin, Germ assignments, to Neoce any, assignors, by me sne 11 Products Corporation,

a corporation of Delaware Application July 9, 1938, Serial No. 218,326

7 Claims.

This invention relates to an apparatus for the mass scale production of articles from dissolved plastic substances by immersion, and has for its object to provide an apparatus of this kind which enables the articles to be produced in a manner free from danger and also permits of recovery of a very large percentage of the solvents.

A further object is to provide an apparatus which is so designed that the complete process of manufacture, which in particular in the production of articles from cellulose derivatives calls for a variously repeated immersion, can be carried out in a complete cycle of operations.

In the production of articles from dissolved plastic substances, and more particularly from cellulose derivatives, solvents are employed which, upon their evaporation, saturate the air within the immersion chamber or the drying chamber to such an extent as to form an explosive mixture.

It is an object of our invention to minimize the dangers of explosion, to remove the solvents from the atmosphere and to recover them for future use as completely and as cheaply as possible.

Solvents may be removed from the atmosphere of a dipping machine, for example, in either one of two known ways; the first being to provide in the machine cooling coils which condense the solvent and allow it to be removed as a liquid; the second being to withdraw the atmosphere from the machine, preferably continuously, and to pass it through a recovery system, usually of the type in which the solvent is adsorbed by activated carbon.

The use of the second process above mentioned is very expensive where large quantities of solvent are contained in the atmosphere to be purified; on the other hand, while the method first above described is simple and cheap, it only partially removes the solvent, and .will normally leave an explosive mixture in the machine to which it is applied, so that opening this machine,

, as to insert or remove the moulds, permits the escape of vapour involving the loss of solvent and contamination of the atmosphere of the factory, and sometimes resulting in disastrous explosions.

We are able to obtain the benefits of both of these methods and at the same time to achieve a rapid and economical recovery of the solvent, and to minimize the danger of explosion and loss of solvent, by dividing the space in which the various operations are performed (for example,

- the dipping operation, the first drying operation and the second drying operation) into a series of chambers, connected together by doors which are normally maintained closed, and which are opened only for the passage of the moulds from one chamber to the other. This separation of the immersion operation from the drying operation, and the division of the drying operation into at least two stages, in addition to accomplishing the economy and safety features above referred to also results in improved quality of the final product.

Considering first the first drying chamber, it will be seen that that is the chamber in which the highest concentration of the volatile solvent occurs, for in that chamber great quantities of the solventcome off from the formed articles as they dry. On the other hand, in the dipping chamber the concentration of the solvent is much lower, particularly because, in accordance with the invention of Bratring application Ser. No. 234,620, filed October 12, 1938, we arrange that the atmosphere in the dipping chamber shall be relatively cool and therefore incapable of sustaining large quantities of vapour. In the second drying chamber a relatively small amount of solvent comes off, so that the concentration of solvent in the atmosphere of that chamber is low. The concentration may be lower still in additional chambers, as, for example, in the charging chamber which we illustrate below.

In any chamber having a high concentration of the solvent, and particularly in the first drying chamber, we recover the solvent by condensing it and withdrawing it as a liquid. We do not allow this chamber to communicate at any time with the air outside of the apparatus; we see to it that it only opens to other chambers which are maintained at lower concentrations of the solvent.

In these other chambers, the chambers of lower concentration, we use the method of solvent recovery which consists in abstracting the atmosphere, as by pumping it out continuously by a fan, and passing it through a recovery system. The result is that in these chambers not only is the concentration of the solvent low, with consequent economy of operation of the recovery system, but the pressure is also low, so that there is no tendency for the atmosphere in these chambers to pass by leakage or through temporarily opened doors into the atmosphere of the factory.

In this manner the whole operation, including the recovery of the solvents, can be continuous; the solvent can be recovered with very little loss V chambers'a'nda charging chamber.

and the danger of fire and explosion is very much reduced, for no chamber in which the concentration of the solvent is high enough to form an explosive mixture is ever allowed to be opened to the air. 7

In carrying out our invention in practice on a large scale we provide a series of chambers, each being connected to the next by an opening which is normally closed by a door, and we provide an endless belt which carries the moulds through the various chambers in succession.

' Normally we begin with the charging'charnber, inwhich the moulds are introduced. 'From this charging chamber the moulds pass onthe endless belt into a clipping chamber, through doors which open automatically toper'mit of such passage and close to maintain the desired separation between the chambers. In this chamher, in which the concentration of solvent is not high, the moulds are immersed in the dipping solution.

. From this dipping'chamber the moulds with fthje"dipp ed articles upon them pass into the "first jdryin g chamber. It is in this chamber that the'highe'st vapour concentration exists and that thedanger of explosions wouldbe greatest :if it communicated directly 'with the outer air. In'fthis chamber we provide cooling coils for separatingjout 'the solvent. The drying of, the moulds and "the condensation 'of the vapours are assisted by the provision in this chamber of an arrangement of heating and'cooling coils "'and bailles which promote a circulation -of air around the moulds and cooling coils.

"Thenfstillon the belt'and still through auto f'matically opening and closing doors, the moulds are carried'itoa second 'dryingchamber. In this'chiamber' the 'concent'ration of the solvent iis'relatively low. ll'he solventis recovered fromthisjchamber' and fro'm'all other chambers in "which"'itsffconcentration 'is low by pumping the atmosphere, out of these chambersand through an'fadsorption device. This serves to keep'the *pre'ssurein' those chambers low, as stated-above. "The, series of three chambers, dipping, first drying and second drying, is repeated *as many timesgas, it "may be desired to dip the moulds, which will depend onjthe thickness the finished "articleshouldhave. 'For articles'such as inexpensive'containers to be used as displaypackages, three'times is usually sufdcient, and accordingly'theapparatus shown in the drawiri'g's'co'mprises ten chambers, i. e., three dip- 'pir'ig, three first drying, three second drying The ten- ,chamberap'paratus'is conveniently arranged in "two'storiesoffi've chambers each. This arrange- ;ment 'aifords the further advantage that the third'dipping chamber maybe located immediately above the second, and'a single bath-lifting device may 'do double duty and serve to lift the dipping jba'ths of both. I

"Inadditiontofthe complete freedom from fdaiig'ena'ndthehighpercentage of the solvent recovered a further advantage arising from di- Jvis'ion'of thet otal production spaceinto single "chambers consistsin the fact that the single operations can now be carried out at different f temperatures. 7 p

Anapplication of Kurt'Bratr-ing, Ser, No. 218,-

ineahsof 'avoiding the formation of bubbles in finished dipped articles, involving ar'elationship "between the temperature'of the dipping bath and I tire-temperature bffthdair into which the clipped m'olds are-withdrawn such that the air is cooler "mentioned Bratring application in a rapid, eco- "apparatus. rigidly connected'to the latter and extends benomical manner.

The invention is illustrated by way of example in; the accompanying drawings, which shows an emb'odiment of the apparatus in which provision 'isimade'for a threefold immersion.

Fig. 1 is a diagrammatical longitudinal section through the apparatus showing a moving belt traversing three immersion chambers, three prelimary drying chambers, three final drying chambersand one charging chamber.

Fig. 2 is a-longitudina-l section showinga part of the -same apparatus onan'enlarged scale, and showing in-addition the arrangement for movement' cf the mould supports in the drying chambers.

Fig. 3 is adiagrammatical elevation 0n the line III-' III in Fig. 2.

Fig. 4 is a diagrammatical view showing a -chamberconnected to a suction blower communieating with an adsorption device.

Refer-ring 'now'to the figures, a two-storied casing I having gastight and heat-insulated walls 2 and-partitions 3 ;is divided by the'latter into ten chambers' i to [3, of which the first five are ion the lower storyand the last five on the upper story. An endlessbeltM passes through all ten chambers, and on this belt are mounted "twentysupports I5 arranged 'ingr'oup's of two over a length corresponding to thelength of a Each of these supports is rotatable These supports carry on their rails l1 extending through the two stories of the The shaft is of each support I 5 is yond the wheel It. At the free ends theshafts l8 carry friction wheels l9, which engage with operating means in a manner whiohwill be described later.

7 On either side of' the support l5 -between the latter and the wheel [6' the shaft i8 is gripped in freely rotatable fashion by grippers 20 on the endless beltin this case a double chain 2!. Each support In is furnished -with slideways '22, into which there are introduced in opposite disposal to one another twomould frames having moulds or cores 23. At each end each support I5 is furnished with four guide mus-24.

In the train of the endless belt or its equivalent, such as the chain 2!, there are provided in the partitions between the. single chambers on a level with and allowing for the width of the rotary supports I5, including their sets of moulds 23, openings 25, which are closed by twopart doors 26. These doors 26 are adapted to open mechanically during the advance of the brought about in any convenient manner, for

example by means of properly placed stops or pins on the moving belt or by coupling the doors with the starting means for the advancing movement.

At the ends of the two-storied casing openings are also provided in the horizontal partition in the path of movement of the belt, these openings being furnished with mechanically actuated doors 21, arranged to be opened and closed in a similar fashion.

On the lower story of the two-storied casing there is provided at one end (chamber 4) the first immersion chamber, furnished with a lifting means which may be a hydraulic plunger 28. This hydraulic plunger acts on two immersion baths 29 (which can be moved into and out of the chamber) to lift them for immersion of the moulds or cores 23 in the plastic solution contained in the baths and to lower them after the immersion has taken place. The chamber 4 is furnished with an outlet 39 communicating with a suction blower. In this way the air in the chamber is sucked up and conducted to adsorption means of any desired kind, such as adsorbers of the activated carbon type. At the bottom of the chamber'4 are provided cooling coil-s 3| serving to cool the air in the chamber, this air in the chamber 4 preferably being maintained at a temperature which is below the temperature of the liquid in the two baths 29.

Following the immersion chamber 4 in the path of the moving belt there is the preliminary drying chamber 5 having heating elements 32, which raise the chamber to the requisite temperature for preliminary drying of the articles on the moulds 23.

As opposed to these heating elements serving to heat the air in the chamber there are provided at the bottom of the chamber cooling elements 33, which not only assist in promoting a continuous circulation of the air caused to ascend as aresult of the heating elements 32, but also condense solvent vapours on their surfaces and thus bring about at the lowest point of the chamber a precipitation of the solvent evaporating during the drying of the articles.

As shown in Fig. 3, there can be provided for creating a directed circulation of the air throughout the chamber 5 auxiliary U-shaped walls 34, which surround the path of movement of the conveying means within the chamber, but leave along the centre of the chamber at the top and the bottom slot-like openings 35, 36, by means of which the air within the said path of movement intercommunicates with the air within the remainder of the chamber. The heating elements 32 are provided on either side in the vertical space between the wall 2 of the chamber 5 and the U-shaped wall 34, whilst the cooling elements 33 are located in the horizontal space between the bottom of the chamber and the wall 34. In this way an ascending current of heated air is produced in the vertical space on either side, this air then entering the central compartment containing the conveying means through the upper opening 35 and enveloping thearticles 0n the moulds 23 in a continuous flow.

The dried and warmed air picks up the solvent evaporating from the articles, becomes cool, again sinks to the bottom whilst washing all articles on the moulds 23 on the support l5, and finally passes through the opening 36 between the U-shaped walls 34 into the horizontal compartment containing the cooling elements 33.

The cooling elements 33 cool the air below normal, so that the solvent vapour carried by the air is caused to be precipitated. This precipitated solvent, which collects along the bottom of the chamber 5, can be withdrawn by means of the tap 31.

Following on the preliminary drying chamber 5 in the path of the moving belt is the final drying chamber 6 which, as indicated in the top portion of Fig. 3 which shows the similar final drying chamber I2, is furnished with heating elements 38 but no cooling elements. To produce a proper circulation of the air the chamber 6 is likewise furnished with two U-shaped walls 39 surrounding the path of movement of the conveying means. As in the chamber 5, slot-like openings 40, 4| are allowed to remain between the walls 39 at the top and the bottom for passage of the'air. The heating elements 38 are provided in the vertical space between the wall 2 of the chamber 6 and the U-shaped walls 39, so that under the thermal action the air is caused to ascend on either side of the chamber and then passes through the slot-like opening 40 into the inner compartment enclosing the conveying means, where it washes the articles on the moulds and, being cooled, proceeds through the lower opening 4| into the outer compartment, being distributed equally on either side.

At a suitable point, which in certain circumstances may be coincident with the bottom of the chamber, there is provided an outlet 42 through which, as. in the case of the immersion chamber, the air of the chamber is conducted by way of a suction blower to an adsorption system. i

The next chamber 1 in the path of the con veyor belt is the second immersion chamber, which in the same manner as the chamber 4 is equipped with a lifting and lowering means 43 for two immersion baths 44, upon the lifting of which the moulds 23 advanced on the supports |5 are again immersed in the plastic solution. The chamber 1 is furnished with an outlet 45 for conducting the air of the chamber by way of a suction fan or pump to the adsorption system, and it is provided with a cooling system 45 similar to that already described in connection with chamber 4 for cooling the chamber to a temperature below that of the liquid solvent in the baths.

The final chamber on the lower story following on the second immersion chamber I, is a preliminary drying chamber 8, which in similar fashion to the chamber 5 is furnished with heating elements 41 for the purpose of heating the air and causing the air to circulate, and with cooling elements 48 for assisting the circulation of the air and also for condensing the solvent vapour inside the chamber. U-shaped walls as already described in connection with the chamber 5 and as shown in Fig. 3 are likewise provided in the chamber 8.

From the chamber 8 the conveyor belt passes to the upper story of the apparatus, the first chamber of which following on the chamber 8 is the final drying chamber 9. As in the case of the final drying chamber 6 the chamber 9 is furnished with air-heating and circulating elements 49, and is preferably furnished with an outlet 59 for connection to the adsorption system.

The next chamber I9 is the third immersion chamber and is, situated immediately above the second immersion chamber 1. The arrangement may be such that by suitable design of the chamber Ill the support 5| for the baths 52 in the chamber l0 can be lifted simultaneously by the lifting means 53 of the immersioncharnber 1.

If the lifting means for thetwo chambers. are

coupled together in' this fashion as shown in Fig. 1, suficient space must be allowed in the supporting structure 53 for the upper chamber'to permit of the passage of the mould support IS with the moulds 23 during the advance of the conveyor belt. This supporting structure, therefore, will preferably be in the form of an arch, although it is also possible to provide suitable connection between the bath support and separate lifting means located at the bottom of the apparatus without departing from the general idea accor ing to the invention. The chamber is furnished with cooling means 5 3, and it may also have an outlet 55 as described in connection with the first and second immersion chambers.

The third chamber in the path of the belt on the upper story of the apparatus is a preliminary drying chamber H equipped with heating elements 56 and cooling elements 51 as already described in connection with the chamber 5. In

this chamber, therefore, provision is likewise made for circulation of the air and immediate condensation of the solvent vapour.

The chamber H is followed by a third final drying chamber l2 which, as shown in Fig. 3, is furnished with heating elements 5'! and an outlet 58,'as already described in connection with the first final drying chamber 6.

The last chamber on the upper story is the chamber l3, which serves as charging chamber for the conveying beltand is furnished with an outlet 59 for connection to an adsorption system both to conserve the vapours which enter from the adjoining chambers and would escape when the chamber I3 is opened for insertion and removalof moulds, and also to maintain a slightly reduced pressure in this chamber to prevent any tendency on the part of these vapours to mingle with the outside air and form'e'xplosive mixtures. I

For the charging and unloading of the supports l5 there are provided (see Fig. 2) in the front and rear longitudinal walls of the chamber I3 apertures 60, which are capable of being closed down and through which the'moul'ds 23 are introduced preferably from the front of the apparatus', whilst the moulds bearin the moulded articles already completed are removed from the supports at the rear. The width of the apertures is preferably such that both supports l5 which. happen to be in the charging chamber can be charged or unloaded simultaneously.

As already described, the supports l5 passing with the endless belt through all chambers of the two-storied casing I are furnished with freely rotatable running wheels l6 (Figs. 2 and 3) running on rails I'I v which extend through both stories of the apparatus. The endless belt is constituted by a double chain 2|, which on either side of the supports I5 grips the ends of the shafts of the supports in freely rotatable fashion between the supports and the wheels l6 by means of grippers 20.

At the two ends the supports l5 possess guide rolls 24, which serve When necessary to guide the supports into a desired position, these supports 15 otherwise being freely rotatable about the shafts it as axes of rotation.

At the points at which the d0uble chain 2| conveys the supports I5 from the one story to the other, and at which there are also located the points of reversal of the conveying chain or belt, thegrippers maintain the wheels IS in close cpntact with the rails ll, which latter likewise xte d t rou e two stories an r m he one to the other inthe path of the chain or belt. 1T0 permit of proper guiding of the supports l5 at the points in question the guide rolls 24 are caused to bear against guard rails 5! and 62 in the manner described in the following:

At the horizontal end of the. rail I! on the upper story there is provided in suitable spacial disposal a horizontal guard rail 6|, which upon the final advance of the supports I5 in the horizontal direction ensures their horizontal position by way of the guide rolls 24 until the chain 2| is deflected from the horizontal direction. Slightly in front of this point, however, the'front guide rolls 24 have been engaged by the guard rails 62. These guard rails are so formed that upon the deflection of the chain 2| and accordingly upon the change over of the wheels it from the horizontal to the vertical direction they guide the supports I 5 by way of the guide rolls 24 in such a manner that the supports 15 are held in a horizontal position. This position is illustrated in dash-dotted lines in Fig. 2.

At the lower point of deflection the wheels I6 leave the vertical section of the rail I7 and, guided by the grippers 26 on the shaft, pass on to the rail I! on the lower story. The guard rail 62 for the guide rolls 24 extends for a short distance in the horizontal direction in the lower story, at the same time a further guard rail 63 taking over the guiding of the lower rolls 24 until the support i5 has reached the operative position on the lower story of the apparatus.

The two chains 2| are driven intermittently by driving means of the conventional kind, the drive being such that upon each advancing movement the chains 2| with the supports l5 are advanced by the length of a chamber. In this way two supports l5 bearing the moulds 23 are moved into or out of a chamber upon each advance. At the positions assumed by the supports l5 during the stationary periods of the chains 2| there are provided actuating means which enable the supports IE to be rotated about their axes. In this connection the arrangement is such that in the dryin chambers 5, B, B, 9, H and I2 the supports l5 are rotated continuously during the stationary periods by a separate drive 64, whilst in the im- 1 mersion chambers 4, 'I and It and in the charging chamber l3 means are provided which permit of a rotation of the supports l5 as desired during the stationary periods of the chain or belt. To permit of this rotation of the supports IS the arrangement, in accordance with Figs. 2 and 3, is as follows:

At each of the points at which the supports l5 are located during the stationary condition of the chain or belt there is provided an endless belt 66 passed about rolls 65 and entering into frictional engagement with the friction wheels i 9 keyed onto the ends of the shafts of the supports l5. Movement of the endless belt 66 accordingly results in rotation of the support I5 about its 1 shaft. The rolls 65, by means of spur wheels 61 and 68,'are in operative engagement with a worm wheel 69, this worm wheel 69 being driven by a worm 10, which is mounted on a horizontal shaft H extending through the drying chambers. The shaft 'II is continuously driven by way of bevel wheels l2, 13 by a driving source, such as an electric motor 64, this driving source driving the Worm wheel shaft H on the upper story as well as the corresponding shaft H on the lower story.

In the immersion chambers 4, 'l and i0 and in but only in accordance the charging chamber I3 there is provided a similar arrangement of moving belt 66 at the stationary-positions of the supports I5. This belt 66 in engagement with the driving wheels I9 is also driven by similar spur wheels 51, 68. On the shaft of the central spur wheel 68 there is provided, however, at these points a sprocket wheel I4, which by means of a chain I5 is in driving engagement with a sprocket wheel I6, which latter can be rotated by a handle TI extending to the exterior 'of the casing.

To permit of a gentle application of this rotary drive to the supports I5 during the stationary periods of the chains 2i the following arrangement is provided:

The wheels I5 moving on the rails II have such a diameter with relation to the wheel I9 that the oncoming support I5 readily passes with the wheel I9 over the endless belt 56. At the stationary position, however, the rail IT is slightly recessed, so that at this point the support I5 with the wheels I9 is lowered and the wheels l9 are thus moved into close contact with the endless belt. .In this way the shaft of the support I5 is firmly coupled with and driven by the central Wheel 68. Upon the advance of the chains the support I5 is lifted with its wheel I5 out of the recess in the rail I'I, so that the wheel I9 is also lifted gently from the endless belt and the operative engagement with the latter is interrupted.

As already described, it is desirable for conveying the supports I5 from one story to another to provide at the end of the upper or the lower story a horizontal guide, which remains in engagement with the guide rolls 25 until such time as the guide rolls have been engaged and taken over by the vertical guard rails 62. At the same time it is necessary to hold the supports I5 rigidly in the horizontal position in the charging chamber when mould frames bearing the moulds 23 are to be applied to the'top of the support I5. On the other hand this retention in the horizontal position should be interrupted immediately it is desired to rotate the supports I5 in the charging and immersion chambers by means of the handle ll.

area of the support. In this way the areas which require to be sealed by the door are kept as small as possible.

A similar intercepting device I9 is also provided shortly before the point at which the conveying belt or chain passes from the preliminary drying chamber 8 on the lower story to the final drying chamber 9 on the upper story, in order also in this case, asbetween thecharging chamber I3 and the immersion chamber 4, to bring about engagement between a horizontal guide 62 and the guide rolls 24. ,f j

The operationof the apparatus is as follows: In the charging chamber I3 the two supports I5 rigidly held in the horizontal position by the guard rails 6| are loaded on the one side with mould frames, whereupon the rail BI is rocked by the lever I8, By means of the handles 11 the supports l5 are rotated through 180, whereupon by actuation of the lever I8 the guard rails 6| are again moved into engagement with the guide rolls 24, and in this rigid position mould frames bearing the moulds 23 are also applied to the opposite sides of the supports I5. Upon the advance of the moving belt or chains the supports I5thus loaded are carried into the first immersion chamber on the lower story. When the movement of the belt or chains has ceased the immersion baths 29 are lifted tothe desired height by the lifting means 28 so asto cause the downwardly directed moulds "onthe supports to be immersed in the plastic solution,

' and the baths are then again lowered. After the To permit of this there are provided in the sta- I tionary positions of the supports I5 in the charging chamber I3 and the immersion chambers 4, I and I9, above the path of movement of the supports I5, guard rails 6| which, however, are pivotally suspended from the top of the chamber and can be rocked laterally by suitable operating means I8, for example by a rocking lever provided on the outside of the charging chamber. In the laterally rocked position, indicated by dotted lines in Fig. 3, the guard rails GI move out of engagement with the guide rolls 24 of the support I5. The support I5 now can be freely rotated about its axis by means of the wheel I9. In Fig. 2 this rail in the immersion chamber on the left has been omitted in order not to interfere with the remainder of the illustration.

In the drying chambers a retention of the supports in the manner described is not required; it is, however, necessary to provide at the passages through the doors intercepting means I9,

which strike against the guide rolls 24 upon the passage of a support through the door and compel the support to assume a horizontal position, so that the door does not require to be dimensioned in accordance with the largest diameter of the otherwise freely rotating support, with the cross-sectional lowering the guard rails 6|" are rocked away, and the supports I5 are rotated through by hand, so that the moulds previously immersed are now reversed in position. To securethis-position .the rail 5| is rocked back against the guide rolls 24, whereupon the immersion baths '29 are again lifted for immersion of the second batch of moulds. After the immersion of this second batch in the plastic substance and the lowering of the baths the guard rails BI are again rocked away and the supports I5 are rotated for a second time through 180, so that the moulds which were the last to be immersed-are again directed upwards, in which position the film of still moist plastic substance on the moulds is somewhat equalized in thickness by'running in the opposite direction. This position isflikewise secured by renewed engagement of the guard rails 6|. 1

Upon the next advance movement of the chains 2I the freshly immersed moulds'i3- on the two supports I5 pass through the doors 26, which are caused to open upon the advance, into the first preliminary drying chamber 5. When the supports I5 move in this chamber 'on to the endless belts 6B and their'wheels "I9 have been caused to engage they commence to rotate continuously, and it is only when the chains 2'I are again advanced that this rotation ceases.

The supports I5 may commence theirmovement in any random angular position,- and are intercepted and moved into the horizontal position before entering the next chamber door by a guard rail 19 similar to that shown in'Fig. 2 with respect to the chamber I2.

The cores or moulds 23, which have been subjected to the preliminary drying action Whilst at the same time being continuously rotated, now pass into the final drying chamber 6, in which, with the conveying chains in the stationary condition, the supports I5 are again continuously rotated about their shafts.

t dby preliminary drying tinder continuous rot tion in the preliminary drying chamber 8 and carrying thereon two layers of plastic. Substance 7 ar oved joy the further advanb' of the sup- Z" s glj thlbli h the next Chamber door into the iininrsion bha'fiiberrl fl, in which the same foiaerat n 7 erstth in the baths, rocking or the guard rails 'revrsalof the'in'oulds, re-engagm'ent of "am rails and iiiim'ersion of the second ta t hi tmh; V I

11 ng onth'thirdiminersion the rnoulds roiidfiotje'djto the third preliminary c anibfer, where they are continuously rotated, ihdJfiji llir iii't'o the last ehaniberhiit the, i. e., thjthitg fihtild tihfg c am r l 2, where likewise 1 Th mamas, or cores gs hearing three layers Pl h l t e ew the e the .eu p t th eh ri i l eei a v n et mm th enerei hamb Bre d. th. he. uppo t eZ d in fife th tiee e v..r 9 .ie flee. meme t e fi e. ,v d mm t we t e; ft eehm uld fi l it tfte ae eee-t A ter theeuers r i .16 .heve' been JQPKQFI awa the We s po ts. i a retiteiiv threat?! lfi j. teene i t nid 1-, T e' eupe eit tr zea e em e .eilth ,i1s6k h j elt hav n the o e lee erel ee femeyeel i e he o te w ha eelel eeel .hyi e h 2 9124 1 h Teteib t e idipee me efie Pref ly ta e .ei2 r th i theh lf ure nt e n sid i. h leh re n ehe leelrw lst the intreidt en f t e .rh tm tilds see n e elinleeni qt tei er 'i elthr tche tsimile eper yr 6e t ee b ite S de eit e.eh eieeehemben ii "th the e he eh e been de c ibed th ne it two ,s pre te I n reu h the. m t ,o t. tieel teel re hthe eete i91- by, h rheqmh ts 3W9 e eh betmte ar allg argeg immersed, dried and dise et esl e mile i e ien-... Iii Fig. 4 there is shown the manner in which, de nden t et l ir dn mree t e r ee the pig 01L of the air takes place in the single gharnbers,

{(s Fig. 3) tli eaiif in the space Between the two 1 ans chsfd tt'ascehd unde the aetion of the t ng elements '32 and thereiipoii passes .fi h the utter fiii n .35 td t e. inn

' tniefit 'froih where it proceeds in thetmaI jQu 11' th lower. opening 36 to the bottom 1th nf r of condensation of the solvent agfinst tlieeoblin'g elements 33; the air ll'ilj diyifi g i zhamtieif l2-situ a'ted above the chamber 5 is suked iip' by a suction blower T6 the outlet at or the ryihgchttmbe l2 therem c ne d I i h wh che d aii fro'ni this; Chamber to the sutti n blower it h siictijdh ower forces the air through th i fi l jfi' ifi 1d '55 T t e ee 'q erewe B hfihl th .bl h t i ht' th Ri e tt ehd iiqej tdipiim thejpip s e ti t th r er tereyieed va gametes in the chaihb'e'rs '4 and 1,

neiftively to the one adsorber (82) or the other (535.

7 outlet 93 and the head 94 phase in Which, bt.m an ,.ai e on. p1 r pperati'oii Further, it is tttth j v The adsorb'e'r's 82, t3 consist of vertical cont'ain'ers having insulated jackets $8, 89. In the upper portion of each of these adsorbers there is provided a grate 9G, or 9!, on'vvhic'h there is piled active carbon, vtvhich has the property of adsorbing on its surface any vapours contained in the surrounding air, i. e., in the present case the s'olven't' vapours. p p ,t When one of the adsorbers is connectednup for adsorption the suction blower w asindicated in Fig. 4, forces the air froth the charnh'er through the open valve Miami the pipe 84 into the ads'orb'er below the grate 93. All remaining 0111;- lets of the adsorb'er are closed, so that under this pressure the air and vapours are forced through the carbon. It is only at the top of the adsorber that there is an open valve 92, which allows the aircleaned by the carbon to pass through the into the atmosphere.

At the top of each of the adsorbers' 82, 83 there is also provided an inlet or 95, to which are connected pipes 91, 9B controlled by valves 99, mil. These pipes 91,,98 are connected to a steam pipe Hll, By means of which, when the valves 99, I09 are opened, steam can be introduced into the top of the adsorbers. I

As shown in Fig. 4, the adsorber 83, when disconnected from the apparatus Chambers by the valve 81', is connected for Washing of thecarhon. For this purpose the steam valve I00 is opened, and the outlet I82 at the top of the adsorber 83 is closed by the valve I03. The steam entering iinder pressure at the top of the fads'orber at E6 is distributed over the entire surfa'ee of thec'arb'on and is forced through the latteiy Upon its passage through the carbonin cohfit'erflow to the adsorption phase the steam removes the solvent which has been adsorbed hy the carbon. .This mixtureo'f solvent and steam aobiimfilates be1ow the grate 9|, and at the bottom of theadsorb'er 83 it can be conducted to a main cbll'ectifig hip'e I'D! byway of the outlet HM, open Valve I85 and pipe I06. it

I the ower Outlet valve I05 of the adsoi'b'er 83 is open during the washirig p ase the outlet valve I09 of the adsorberl 82 Connected in parallel by way of the pipe W8 is naturally closech The air frorh the Chambers connected to the adsorption sy tem, for example in Fig. 4 theair from the 'cha'inbern, is conducted selectively -b'y the blower 19a to t h on'e adsorbtr or the other almost up to the coin'ple'te adsorption capacity, whilst the econd ahsorher is in v, the washing phase; This is carriedout alternately. h f

At the same time it isfnecessam during theopleration to interpofse asa'ihird phase a cleaning m2 rreth h t is' sucked 11h bylwayl of the inta e p pe in; and bywa t the valves L2,. than? associated pipes 4,4, 1,5 ihielct'td; selectiveh'intp the aqserbehsz or glbelow the active carbon, being discharged into the Inosphere aboye the active carbon ax'ter the opening of the up'per'outl w a v 9 6 lD -M v. t w l E lm tha t 1ets 3ll;

immersion afihara usleanl eithi rbe ee nee edi cdm'nioii to a dohble-adsorptionsystem as irij'ig. 5 thiteieh f eehai h s 45,5 1; 9;, l 1, and I3 may have a separate adsorptionsystemj, these systems t en being connected r 1: alternate I possible to prqriid tthe sth t e eiy l fiee s h h'ihd th u ion hitters 19 Q'iiitfg'eneially it will be understood that no limitation is made to the specific embodiment illustrated in the drawings, and that numerous modifications are quite possible within the meaning of the above description and the annexed claims without departing from the spirit of the invention.

What we claim as new and desire to secure by Letters Patent is:

1. In an apparatus for forming articles by dipping molds in a solution containing a volatile constituent capable of forming with air an explosive mixture, a plurality of chambers in which difierent operations are performed and in the atmosphere of which concentration of the volatile constituents is normally different, the chamber having the highest concentration of the volatile substance opening only into a chamber having a lower concentration, and not directly to the air.

2. In an apparatus for forming articles by dipping molds in a solution containing a volatile constituent capable of forming with air an explosive mixture, a dipping chamber, a primary drying chamber connected to said dipping chamber and a secondary drying chamber connected to said primary drying chamber, each of said chambers being separated from its adjoining chamber by a displaceable closure means one of said chambers normally containing vapours of said constituent in a concentration such that if mixed with air the resulting mixture would be explosive, means for condensing said vapours in said chamber, means for avoiding direct communication between said last mentioned chamber and air outside of the apparatus, and means for withdrawing the atmosphere from another of said chambers and for removing said volatile constituent therefrom.

3. In an apparatus for producing articles by dipping moulds in a solution containing a volatile constituent, a plurality of chambers in which different successive operations are performed, means for conveying said moulds successively through said chambers, at least one of said chambers opening to the outside of the apparatus and at least one other opening only to another of said chambers, and means for maintaining a negative pressure within such of said chambers as open to the outside of the apparatus.

4. In an apparatus for producing articles by dipping moulds in a solution containing a volatile constituent, a plurality of chambers in which different operations are performed, at least one of said chambers opening to the outside of the apparatus and at least one other opening only to another chamber, means for condensing vapours of the volatile constituent in a chamber opening only to another chamber, and means for sucking the atmosphere from a chamber which opens to the outside of the ap- Daratus.

5. In an apparatus for producing articles by dipping moulds in a solution containing a volatile constituent, a plurality of chambers in which different operations are performed and in the atmosphere of which the concentrations or the volatile constituent are normally diiierent, a chamber in which the concentration is high opening into a chamber in which the concentration is low and not to the outside of the apparatus, means for condensing vapours of ti e volatile constituent in a chamber in which the concentration of the volatile constituent is high, and means for sucking atmosphere from a chamber in which the said concentration is low.

6. In an apparatus for producing articles by dipping moulds in a solution containing a volatile constituent, a plurality of separate chambers in which different operations are performed and in the atmosphere of which the concentrations of the volatile constituent are normally different, the chamber in which the concentration is high opening into the chamber in which the concentration is low, and not to the outside of the apparatus, means for condensing vapours of the volatile constituent in a chamber in which the concentration of the volatile constituent is high, means for sucking atmosphere from a chamber in which the said concentration is low and for maintaining a negative pressure within said chamber, a solvent recovery apparatus, and means for passing said atmosphere to said solvent recovery apparatus.

7. In an apparatus for producing articles by dipping moulds in a solution containing a volatile constituent, a plurality of chambers in which different operations are performed, means for conveying said moulds successively through said chambers, at least one of said chambers opening to the outside of the apparatus and at least one other of said chambers opening only to another of said chambers, means for condensing vapours of the volatile constituent in a chamber opening only to another of said chambers, means for withdrawing the atmosphere from that chamber which opens to the outside of the apparatus, and means for recovering solvents from the atmosphere withdrawn from said last-named chamber.

ALBERT BOECLER. KURT BRATRING. 

